Telephone system



/NVE/V TOR J. C. KELLY ATTORNEY May 38, 3937. J. c. KELLY ZSA@ TELEPHONE SYSTEM Filed Deo. 18, 1935 0o ogn c D ooo m /Nl/ENTOR J. CKELLV ATTORNEY May ma w37- J. c. KE| n Y TELEPHONE SYSTEM Filed Dec. 18, 1935 ZSASS '7 Sheets-Sheet 3 /NVE/VTOR J C. KELLY A7' TURA/EV May i8, i937. J. c. KELLY 2,080,485

TELEPHONE SYSTEM Filed Deo. 18, 1935 '7 Shets-Sheet 4 F/G. 7 E

MARG/NAL RING/Ns /Nl/ENTOR J. C. KELLY May 18, 1937. J. c. KELLY- TELEPHONE SYSTEM Filed Deo. 18, 1955 7 sheets-sheet S /NVENTOR J. C. KELLY ATTORNEY o ooooooou k u m9 n .mo @Ew May 18, 1937. J. C. KELLY 2,080,486

` TELEPHONE SYSTEM Filed Dec. 18, 1935 '7 Sheets-Sheet 6 /N l/E/v TOR J. C. KELLY BVQMW ATTORNEY May 18, 1937. J, C, KELLY 2,080,486

TELEPHONE SYSTEM Filed Dec. 18, 1955 7 Sheets-Sheet 7 CONTROL /NGNG RELEASE /0/9 [006 :5

/NVE/VTOR J. C KELLV A TTORNEV Patented May 18, 1937 UNiTED STATES PATENT OFFICE TELEPHONE SYSTEM New York Application December 18, 1935, Serial No. 55,058

24 Claims.

This invention relates to telephone systems and particularly to automatic systems in which connections between subscribers lines in one exchange may be established under control of an operator at a distant exchange.

An object of this invention is to improve and simplify the operation and control of circuit arrangements used in systems of this kind.

Heretoiore systems have been provided in which l a subscriber at a local exchange may initiate a call by operating his hand generator and thereby cause the nder switch of an idle link in the local exchange to find his line and to signal an operator at the distant exchange over a remote control trunk. The operator answers the call and dials back over the same trunk and thereby causes a connection to be established from the calling subscribers line over the finder, link and a connector to a called subscribers line. The operator then iings said subscriber and retires from the connecon.

Systems of this type have also been provided in which when a calling subscriber initiates a call the operator at the distant exchange is signaled and when the operator begins to dial a called number the calling subscribers line is associated with an idle link through the operation of relays and when dialing is finished, the called subscribers line is associated with said link to establish a connection between the calling line and the called line.

It is a feature of this invention to provide in systems of this kind, means whereby when a calling subscriber initiates a call, the operator is signaled over a remote control trunk without connecting the subscribers lines to an idle link and when the operator answers the call by connecting la cord to the trunk, an idle preselected vlink is associated with the calling line for the extension of 1U a connection to a called line. This feature may be employed in a system where a line-iinder is operated to connect the calling line to an idle link when the operator answers.

Another feature is an arrangement whereby .D when the operator starts dialing the called subscribers number over the remote control trunk, the calling subscribers line is disconnected in the link from the trunk and whereby if she does not desire to remain on the connection after she has ,U rung the called subscribers line, the removal of her cord circuit from the trunk causes the connection to be established between the calling line and the called line over the link and the trunk connected with the next idle link, or if the oper- 55 ator does desire to remain on the connection, the

operation o'f a certain key and dialing of a special digit causes the reconnection of the calling line to the trunkin the link and the lconnection of the K calling line. with the called line through the link. Another feature is an arrangement, in which the Vremote control trunk is normally connected with an idle link, whereby when this link becomes engaged in a connection between a calling line Aand a called line the trunk may be disconnected from said link and connected to a succeeding idle link. A rotary switch is employed to transfer the trunk and the switch is operated when the operator releases the trunk after it hasgbeen used for the establishing of a connection through an idle link. Another feature is an arrangement whereby if all links vare busy they may be tested for busy conditions vby the operator over the remote control trunk and if required the connection through a link may be released and the link made idle. If an all link-busy signal is received when the operator seizes the trunk, she may by dialing the digit 1 connect the trunk with the first link and when she has monitored or tested the condition of this link, she may dial the digit 1 again and cause the trunk to'be connected to the next link and so on kuntil all links have been tested. If a connection A'through a link under test is held busy and no conversation is taking place indicating that the subscribers have neglected to release the connection by transmitting a ring-01T signal the operator may, by sending such a ring-01T signal over the trunk, release said connection.

Another feature is an arrangement whereby the operator may initiate a call to a called subscribers line vover the remote control trunk through the link associated therewith. The seizure of the trunk causes the line-nder of the associated link to advance to a special position to mark the call as -incoming over the trunk. This line-finder is returned to normal position when the connection is released.

Another feature is an arrangement whereby if a call is in progress, the remote control trunk lamp vat the operators position is flashed if another subscriber attempts to establish a connection. The arrangement is such that, if the operator .is dialing over `one of the conductors of the remote control trunk when the second subscriber calls, the trunk lamp is flashed by means including the interrupting of the current on the other conductor of the trunk.

Another feature is an arrangement whereby if a pay station subscriber calls, the remote control trunk lamp signal at the operators position is lighted, after she has answered the call, for a short interval vto indicate to the operator that a pay station is calling. The calling pay station subscriber at the same time receives a tone. This may be accomplished by means of a circuit closed when the line relay of the pay station line is operated, to eiect further circuit operations that cause the signal to be operated and the tone to be applied.

Another feature is an arrangement whereby in case of a call to a busy subscriber when the called subscriber is on a party line and engaged in a revertive call, the operator will not receive the usual busy tone, but the remote control trunk will instead be connected to the called line and the operator will consequently hearthe conversation and thereby know that the called line is busy in a revertive call. The calling line will also be connected momentarily to the called line so that the calling subscriber will consequently by hearing the conversation know that the called line is busy in a revertive call. The operator then releases the connection from the called line. This Vmay be accomplished by means whereby the usual busy test relay operates, as if the called line were idle, to cause the establishing of a `connection from the trunk to the called line and bymeans whereby the operator by operating a key, dialing a special digit and transmitting k ringing current causes the calling line to be momentarily connected to the called line and the connection to the called line released.

Another feature is an arrangement for establishing incoming toll call connections to a subscriber in the local exchange, whereby an operator at a distant exchange may by seizing a talking trunk line leading to the local exchange cause the operator to be signaled over the remote control trunk, whereby the operator then seizes the remote control trunk and thereby causes an idle link to be associated with the talking trunk, whereby the operator then by dialing the desired subscribers number and ringing the called subscriber thereby causes a connection to be established to the called subscribers line and the called subscribers bell rung, whereby the operator then releases the remote control trunk and thereby causes said trunk to be associated with another idle link and a connection established between a called line and the talking trunk over said first mentioned link and whereby the operator then extends the connection over said talking trunk to a connection beyond, such as a toll trunk over which the connection to the called subscribers line in the local exchange was desired.

This invention has been illustrated in the accompanying drawings in which:

Fig. l shows in diagrammatic form a typical arrangement of a remote control exchange and trunks connected to a manual exchange and to a step-by-step exchange arranged to illustrate the features of the invention.

Figs. 2, 3 and 4 show how the succeeding Fig'- ures 5 to l0 may be arranged for the description of the detailed circuit arrangements as shown in the succeeding gures embodying the various features of this invention.

Figs. 5, 6 and '7 arranged in accordance with Fig. 2 show the detailed circuits of the remote control exchange with a remote control trunk and a talln'ng trunk leading to a manual exchange.

Figs. 8, 6 and 9 arranged in accordance with Fig. 3 show the detailed circuits of the remote control exchange with a talking trunk between the remote control exchange and a step-by-step exchange having multiple connections to a manual exchange, a talking trunk between the remote control exchange and the manual exchange and a remote control trunk between the remote control exchange and the manual exchange; and

Figs. 5, 6 and 10 arranged in accordance with Fig. 4 show similar arrangements with a remote control trunk to the manual exchange arranged as a phantom circuit in connection with two ordinary telephone lines or trunks leading to the manual exchange.

Referring now to the drawings and particularly to Fig. 1, three exchanges have been shown in diagrammatic form, a remote control exchange A, a manual exchange B and a step-by-step exchange F. Connections between the subscribers at these exchanges and operators at the manual exchange may be controlled and established over the remote control trunk |02, the talking trunk |03 and the talking trunk |09. At exchange A ive line-linders LF have beenyshown connected to links to corresponding connectors C through which connections may be established between subscribers and between subscribers and opera- |04 has been shown through.

tors. A switch which connections may be established between the remote control trunk |02 and the links.

Detail descriptions will be made as follows of various calls and circuit conditions that are possible with the circuit arrangement shown in the drawings.

With Figs. 5 to 7 arranged as shown in Fig. 2, a call from the subscriber at |00 to another subscriber in exchange A over a line-finder F through the associated link and connector C under control yof the operator at D in exchange B, over the remote control trunk |02.

A call from the subscriber at |00 to another subscriber at exchange A where said other subscriber is on the same line, that is, a revertive call.

A call from the subscriber at |30 to another subscriber at exchange A with the subscriber at |30 equipped with pay station apparatus.

Descriptions will be made of the conditions arising if a call from the subscriber at |00 is attempted and the remote control trunk |02 is busy and if a call from the subscriber at |00 is attempted and all the links are busy.

A call originated by the operator at D in exchange B over the trunk |02 to a subscriber in exchange A.

Description will be made of testing of the links inl exchange A by the operator at D in exchange B.

Description will be made of conditions arising if all the links have been taken for use and then one of said links becomes idle, for preparing said idle link for use on the next call by associating the remote control trunk with said link through the switch |04.

A description will be made of a toll call to a subscriber in exchange A, to be controlled and established by the remote control operator at D in exchange B, and extending from atoll trunk incoming to exchange B through a cord and over the talking trunk |03 toV exchange A, and of a toll` call from a subscriber in exchange A, controlled and established by the remote control operator at D, and extending over the talking trunk 03 to exchange B through a cord and out over a toll trunk from exchange B.

With Figs. 8, 6 and 9 arranged as shown in Fig.

3, a description will be made of a call from the subscriber at |0| in the step-by-step office F through a line-finder |06, selector |01 and conf nector |08 over talking trunk |09, the line-finder LF and associated link and connector C to the subscriber at |00 under control of the remote control operator at D in exchange B.

A call will be described from the subscriber at |00 over line-iinder LF, the associated link and connector C in exchange A, over talking trunk |09 through the line-nder |06, selector |01 and connector |08, to the subscriber at |0| under control of the remote control operator at D in exchange B.

A description will be made of a toll call incoming over a toll trunk to the exchange B' for a subscriber in exchange A, controlled and established by the remote control operator at D in exchange B, and extending from the toll trunk through a cord and over the trunk |00.

With Figs. 5, 6 and 10 arranged as shown in Fig. 4, descriptions will be made of all the various calls and circuit conditions that are possible as described above in connection with Figs. 5, 6 and '1 arranged as shown in Fig. 2. The only difference in this case is that the remote control trunk is a phantom trunk circuit derived from two ordinary telephone circuits between exchanges A and B.

Referring now rst to the arrangement of Figs. 5, 6 and '1 according to Fig. 2, a description will be made of a call from a subscriber at |00 to another single line subscriber in the same exchange. When the subscriber at |00 decides to make such a call he originates it by operating his hand generator. His line relay |06 thereby operates through its upper winding and the conductors to the subscriber at |00 and theupper outer armature and back contact of this relay. When this relay operates it breaks this connection at the upper armature and back contact and locks itself from battery through its lower winding, lower inner armature and vfront contact and a connection through the secondary winding of the induction coil 000 to ground. Relay |06 in operating removes a ground from the test bank contact of the line-lnder LF bank A circuit is also closed by relay |06 for relays 00|, 602 and 100. The circuit for 50| extends from battery through the left-hand winding of this relay, lower outer armature and front contact of relay |06 to ground. The circuit for relay 602 extends from battery through the winding of this relay, contacts of relay 003 to ground at relay 06 and the circuit for relay 100 extends from battery through the winding of this relay, contacts of relay 603 to the same ground as relay |06, Relay 60| is a differentially wound relay so that when the circuit through its right-hand winding is closed to the ground at relay 60| it vibrates by the alternate discharges of the condenser 004, and generates a tone in the primary winding of induction coil 600 which is induced in the closed circuit through the secondary winding of the induction coil and the lower winding of relay |06. The tone in this circuit induces a tone in the circuit through the upper winding of relay |06 closed at the upper outer armature and front contact of this relay and the calling subscribers line and becomes audible to the calling subscriber |00. This tone serves as an indication that the call has registered. Relay in operating closes an obvious circuit for the operation of relay 10| which in turn closes a circuit for the tip and ring conductors of the trunk |02 to the operator at D at the manual oice B to light the operators line lamp 104 to indicate that a call from a subscriber in exchange A is initiated.

It will be notedzthat normally a circuit is completed vfrom the batteryy 105 to battery v|05 to charge `this latter battery when the trunk is not in use. This circuit may be traced from battery 105; winding of relay 1.08, contacts of relay 109, contacts of key "H0 over the tip conductor' of trunk |02, upper armature and back contact of relay 10|, winding of relay 1|| to battery 106,

and from battery 105, winding of relay 108, con-k.

tacts of relay 109, contacts oi, relay 108,v the ring conductor, contacts of Vrelay 10i, contacts a-nd winding of r-elay 1H to battery 100. This normally maintains relays 108 and 106 operated. When vrelay 10| is operated these circuits are opened and relays 108 and 1|| are released. The release of relay 108 closes a circuit for the operation of signal 104 from battery through contact of jack 1|2, right-hand armature and back-con tact of relay 108, contact of relay 109, lamp 104 to ground at contacts of control key 1|3.

When the control operator at D now answers the call 'by vinserting plug 1 |4 of her usual cord circuit in the jack 1|5, relay 109 is operated over Y an obvious circuit closed by the springs of jack 1|5. This opens the circuit for lamp 104 which now is extinguished and the operator may .now Y throw the talking key in her cord circuit to answer thecalling subscriber. Relays 1|6 and 'H1 are now operated due to the operation of relay 100=Over a circuit from Abattery through cori-- tacts of relay 1| 0, Vrighthand winding of relay 1|1, contacts of relay 109, contacts of key 1|9, ring conductor, lower armature and front contact of relay 10|, lower right-hand winding of induction coil 12|, winding of relay 1|6, contacts of relay 122,` to ground. Relay 1|6 in operating closes a circuit to ground at its lower armature and front contact for relay 123 for the subsequent operation of this relay through the tip conductor over trunk |02 as will hereinafter be described. A circuit is also closed Yby the operation of relay 1|6 for the operation of relay 600 from battery, winding and the vibrating' contacts of the step-by-step magnet 601 of switch |04. winding of relay 606, upper armature and front contact of relay 1|6, upper outer armature and back contact of relay 122 to ground. The magnet 601 does not operate in this circuit. Relay 006 in operating places a ground at its outer right-hand armature and front contact through the winding of relay 10| to battery and holds this relayoperated. Relay 600 in operating also closes a circuit as follows: battery, winding of the `stepping magnet ||0 of line-nder LF, selfinterrupting contacts of this magnet, first con tact and brush of bank 3 of the switch |04, inner right-hand armature and front contact of relay 0.00. Winding o-f relay 6|0 to ground. It is assumed that in this case the link shown in Fig. 5 has been preselected by the switch |04. The switch |04 is resting on its first contacts and the link shown in Fig. 5 is therefore the first link. In this Acircuit there is a provision for four other links of the same kind, which are connected for use by switch |04 as this switch is advanced, in a manner that will be hereinafter described. Ii the line-nder LF does not have its brushes resting on the terminals of the calling line there will also be a circuit connection made at this time from ground at the lower outer armature and back Contact of the line relay that is connected to a contact on bank of the line-iinder in whatever position the line-finder may be at this time so that the brush of this bank will extend this ground to the rst contact and brush of bank 2 of switch |04 to the outer right-hand armature and back contact of relay R to the winding of relay 6|0. Thus relay 6|0 will be short-circuited and will not operate at this time. If as stated thel line-iinder is not resting on the calling line, the stepping magnet operates and advances the brushes until a terminal on bank I on Which there is no ground is reached which will be the calling line as relay |06 of this line is operated. The line-iinder then stops on the terminals of the calling line and the shunting connection for relay 6| 0 will be removed so that this relay will now operate. The resistance of the winding of relay 6|0 is such as to prevent further operation of the stepping magnet |0. Relay 6| 0 in operating closes a circuit for the operation of relay 603 from battery through the winding of this relay middle right-hand armature and front contact of relay 6|0 to ground. Relay 6|0 also shunts the line relay |06 so that it releases, the shunt circuit in this case extending from battery, contact and brush of bank of the line-lnder LF, contacts of relay contacts of relay ||2, the

first contact and brush of bank of switch |04,

left-hand armature and front contact of relay 606, inner right-hand armature and front contact of relay 6|0, to ground at the outer lefthand armature and back contact of relay 6|3. As relay |06 now releases the tone to the calling subscribers line will be removed. The operation of relay 603 prepares a circuit for the subsequent operation of relays and ||2 in the link circuit and causes the release of relay 602. Relay 603 also prepares .a transmission circuit by closing a circuit at its third outer left-hand armature and front contact for the left-hand windings of repeating coil 12|. The tip and ring conductors from the calling line are now connected through the tip and ring conductors of the trunk |02 to the distant operator over a circuit as follows, from the tip and ring conductors of the calling line at |00, contacts of banks 3 and 4 of the linender LF, armatures and contacts of relay ||4, rst contacts and brushes of banks 5 and 6 of switch |04, contacts of relay 124, left-hand windings of repeating coil 12|, and through the abovementioned contacts closed by relay 603, the transmission circuit for the trunk being closed through the right-hand windings of repeating coil 12|, through contacts of relay 10|, condensers and 1,26, contacts of relay '|l8, lefthand windings of repeating coil 121, while the right-hand windings of this repeating coil are closed through the jack 1|5 and plug 1|4 to the cord circuit of the operator at D.

The operator may now talk to the calling `subscriber at |00 and if the subscriber should desire to extend a connection to another line in the same olice A, the operator will dial back over the trunk to obtain the number desired. The operations of these circuits are as follows: To dial the desired number, the operator inserts plug |30 into jack 1|2 to connect dial 13| to the trunk for dialing. He then operates his dial and as the dial moves from normal, relay 1|8 is operated from the battery, oil-normal contact of dial 130, sleeve contacts of jack 1|2 and plug 130, winding of relay 1|8 to ground.`

Relay 1|8 in operating opens a connection from the trunk toi the operator at its outer upper and lower armatures and back contacts. Relay 1|8 also opens the connection to battery at its upper inner armature and back contact for the control circuit over the ring conductor, but battery for this circuit is substituted through the dial contacts of the dial 13| and tip contacts of jack 1|2, plug 130, left-hand winding of coil 132, lower inner armature and front contact of relay 1|6,

outer left-hand armature and front contact of relay 109, contacts of ringing key 1|9 to the ring conductor of the trunk |02 to maintain relay 1|6 operated. As the dial returns to normal the dial contacts open this circuit and relay 1|6 responds to the pulses. At the rst pulse relay 1| 6 releases and opens the circuit for relay 606 and closes a circuit for the stepping magnet ||6 for the connector C as follows: from battery through the winding of this magnet IIE, winding of relay H1, upper middle armature and b-ack contact of relay first contact and brush of bank 4 of switch |04, middle right-hand armatureY andr front contact of relay 606, upper outer armature and back contact of relay 135, upper armature and back contact of relay 1|6, to ground at the upper outer armature and back contact of relay 122. Relay ||1 operates and remains operated with relay 606 during the pulsing as both are slow to release. The operation of relay ||1 closes a circuit for the operation of relay ||4,

from battery, inner left-hand armature and front contact of relay 603, inner left-hand armature and front contact of relay upper winding of relay ||4 to ground. Relay ||4 provides a locking circuit for itself from the battery at relay 603, upper middle armature and front contact of relay ||4, resistance H9, upper wind ing of this relay to ground. The operation of relay ||4 removes the calling subscribers line from the talking connection at its upper and lower outer armatures and back contacts. The connector C is now advanced in accordance with the dialing to the desired subscribers line. the end of the dialing relay 1|6 remains operated while relay |1 releases.

If the called line is busy the wipers of connector C will encounter ground on the brush of bank 5 and relay |20 will not operate when the relay |1 is released, as the circuit closed through the right-hand winding of this relay is also connected to ground. A circuit will therefore be closed for the operation of relay 6|5 from battery through the lower armature and back contact of relay 135, left-hand winding of relay 6|5, middle left-hand armature and back contact of relay 6|3, outer left-hand armature of back contact of relay I1, outer right-hand `armature and back contact of relay |20, second lower armature and front contact of relay ||4, the brush and a corresponding contact of bank 2 of the connector C to ground. Relay 6|5 in operating closes an obvious circuit for the operation of relay 6|6 and this relay in turn closes an obvious circuit for the operation of relay 6|3. Relay 6| 3 ink operating opens the circuit for relay 6 5 which now releases and this relay in turn releases relays 6|6 and 6| 3. These operations are then repeated causing an intermittent busy tone to be placed on the ring conductor of trunk |02. As relay 6|5 operates it closes an obvious circuit for relay 60| each time it operates causing thisk relay to transmit the tone over ythe ring conf ductor through the condenser6|1 and the lower aofise from battery contacts of relay 1| 8` through the left-hand Winding of relay 1|1, contacts of relay 109, normal contacts of release key lle, over the tip conductor, contacts of relay 16|, upper right-hand winding of the repeating coil-12|, make-before-break contacts of relay"3||, `winding of relay 123 to ground at the lower armature and front contact of relay 1|5. The circuit for relay 123 now extends through contacts of key H3, terminal of jack 1|5 to battery through coil 132. Relay 123 operates in this circuit and closes an obvious circuit for relay 122 and this relay in turn closes an obvious circuit for the operation of relay'135.V The operation of relay 122 places a holding ground ior maintaining relay E06 operated at its lower inner armature and iront contact andopens the circuit for relay 'H6 at its lower outer armature andback contact; while relay H5 nowreleases a circuit for relay 123 is maintained at the ground placed at the ylower armature -and front contact ofrelay 122. Relay 135 inoperating opens a circuit for the step-by-step'magnet I 6 of connector C, which would have been closed when relay 1|6 was released. Relay 135 -removes the battery at its lower armature and back contact for the circuit for relay SI5 which therefore releases so that the busy tone will now be stopped. Relay 135 closes a circuit vfor the operation of relay from battery through the lower armature and front contact of relay v135, lower winding of relay to ground. vRelay in operating enables the operator to monitor and challenge on the called line by closing a circuit from the called line through contacts and brushes Aof banks 3 and 4, upper and lower outer armatures and front contacts of relay ill, rst contacts and brushes of banks 5 and E of switch |04, contacts ofrelay 124, the left-hand windingsof repeating coil 12|, contacts of relay-'653, while the connection to the operator is closed through the right-hand windings ofthis 'repeating coil 12|, contacts of relay 10|, contacts of release key 1|0, condensers 125 and 126, windings oirepeating coil 121, terminals of jack 1|5 and plug A1|4 to the operator at D. The operator may now ascertain the condition of the line and if it is busy the operator will release the control key 1|3, and operate the release key 1|0. This releases `relay 123 which, in turn, releasesrelays .122..and 135. As relay 135 is slow in releasing va momentary circuit is closed `for ythe release of relay i4. This circuitk extends from battery through Ithe lower winding of relay H4, Ylower inner armature and front contact of this relay, upper inner armature and back contact of relay `122v and upper inner armature and iront Contact of relay 135, outer left-hand armature and back contact of relay H1, outer right-hand armature and back contact of relay |25, second lower varmature and front contact of relay H4 toground at the brush and the corresponding contact of bank 2 of the connector C. Relay `i i4 now releases as it is diierentially wound. The-operator-willnow be able to talk to the calling subscriber over the calling loop again closed at the outer upper and lower armatures and back contacts of relay H4.

If vthe line is busy and engaged ina revertive call, that is, between subscribers ori-the same line the line relay of that busy line will not be operated. Consequently, when relay H1 releasesafter dialing relay will operate from the battery at -the line relay of this busy line through the corresponding contact and brush of magnet 5 ofthe connector C, the second lower armature and back contact of relay III, inner right-hand armature andback contact of relay ||1, right-hand Winding of relay |20 to ground. The operator will then proceed as usual by operating the control Vlkey 1|3 to connect her line to the called line for monitoring. The operation of the control key 1|3 operates relays 123, 122 and 135 and relay as hereinbefore described. As relay |20 is operated the circuit for relay 6 6 will not be completed and hence there will be no busy tone in this case. As the operator is now connected to the called line she will hear conversation and know thereby that the line is busy in a revertive call. She will then release the control key 1|3 and operate the release key 1| 0'. This causes the release of relays 123, 122 and 135 and causes the operation of relay TIS. It should be noted that inv this-case between the release of relays 122 and 135, relay||4 will not be released through the circuit over its lower Winding which was momentarily closed between the release of relay 122 and the yrelease of relay Y135 as this circuit is `opened at the outer right-hand armature and back contact of relay |20. Hence, in this case vthe'operator will have to release the connection by rst dialing a number, for example, the digit 3. On the rst release-of relay 1|5 in response v tothe dialing,a shunting circuit is closed for releasing relay ||4. This shunting circuit extends irom'ground at the outer armature and back contact of relay 122, upper armature and back contact of relay 1|6, upper outer armature and back contact of relay E35, middle right-hand armature 1 and frontcontact of relay 60S, first terminal of `bank 4 of switch |04, second upper armature and front contact of `relay resistance ||9, upper Winding of relay ||4 thus causing the release of relay H4. Relay ||4 in releasing closes the circuit for the voperation of relay ||2 from battery,

outer left-hand armature and front Contact of relay |20, third lower armature and back contact of relay l I4, winding of relay ||2 to ground.

Relay |2 in operating connects the calling subscr1ber.s line with the called subscribers line at `the upper and lower outer armatures and front contactsand thus the calling subscriber will hear .theconversation over the called line as engaged ina revertive call connection. Theoperator will fthen immediately again operate her control key f 1|3 toclose the circuit for relay 123 as herein- Y before described. This relay closes the circuit for the ringing=relay 136and the operator will then operate her ringing key'1l9 momentarily to operate relay 136 and transmit, as before, a ringing signal torelease lthe connection by the operation of relay |23 over a circuit from the tip and ringl conductors of the connection between the line finder andthe connector, .the inner left-hand armature and back contact and left-hand Winding ofrelay |23. Relay |23 in operating is locked through its right-hand winding from battery j through its-inner right-handarmature and front contact, vthe right-hand winding to ground at armature and back contact of, relay inner right-hand armature and back contact of relay H1, right-hand winding of relay` |20 to ground.

, The operation of relay |20 in turn completes V.a circuit for relay from battery, innerY left-hand armature and front contact of relayl 603, inner right-hand armature and frontV contact of relay |20, upper winding of relay V| to ground. Re-

lay in operating completes a locking circuit for relay |20 from battery, left-hand winding and inner left-hand armature and front contact of this relay, upper inner armature and front contact of relay lto ground at the brush and the corresponding contact of bank 2 of the connector C. Relay l I in operating grounds the test terminal,.the called line at its second lower armature and front contact, the ground being supplied at the upper outer armature and back contact of relay 124. `Relay HI in operating` completes the connection'to the called line over banks Y3 and 4 ofv the connector C to the trunk |02 ashereinbefore traced.

The operator may now ring the called subscriber. Before the ringing key 1|9 is operated, the operator must operate the control key 1|3. The operation of this key causes a marginal relay 123 to operate-as hereinbefore described and this relay in turn operates relay-122 which prepares apath for the alternating current responsive relay 136. Relay 122 when operated maintains the ground connection for the Vrelay 123 and opens the circuit for relay 1 I6 which releases, and places aholding ground `for relay 606 to prevent this relay from releasing. Relay 122 also operates relay 135. The operator now operates the ringing Ykey 1|9 and ringing current extends out over the vring conductor of the trunk,|02, over contacts f relay 10|, lower right-hand winding of repeating i coil 12|, upper armature and front contact of relay 123, condenser and winding of relay 136 to ground. Relay 136 operates and closes an obvious circuit for relay 124 and this relay closes a path trom the ringrconductor of the trunk contacts of relay 124 `over the called subscribers loop and back to ground at contacts of relay 124. When the relay 124 operates the shunt ground for the lower winding of the line relay of the called subscriber corresponding to line relay |06 is removed allowing this line relay to fully operate each time the operator rings down on the line.Y Each time relay 12d releases the called subscribers line relay will be shunted down again.v This circuit may be tracedfrom ground, upper outer armature and Y back contact of relay 124, outer right-,hand armature and back contact of relay ||1, middle lower armature of relay brush and corresponding terminal of bank 5 of connector C, to battery at the line relay of the called subscriber corresponding to relay |06 of the calling subscriber.

When the called subscriber answers the operator either withdraws from the bank and cornpletes the connection between the subscribers'or remains on theV connection to monitor-the call. If the operator wishes to remain shefwill release the. control key 1|3 and operate the release key 1| 0 causing relay 123 to release which, in turn, releases relays 122 and 135 and allows relay 1|6 to reoperate. She will then dial for' example digit 3. This allows a ground impulse to momentarily shunt the holding winding for relay lll as hereinbefore described causing this relay to Arelease and'this, in turn, causes Ythe operation of relayv If the operator desires to leave the line shed will release the control key to release relays 123,- 122 and 135 and operate relay 1|6. `She will then withdraw her plug 1 |4 from jack 1 I5. 'I'nis causes the release of relay 1|6. This causes a momentary impulse to release relay ||4 as hereinbefore described. In this case,.however, relay 1|6 in releasing causes the release of relays 606 and `603. Relay 603 in turn releases relay The release of relay ||4 allows Arelay ||2 tooperate and connect the calling and called together as hereinber fore describedand also completes a holding kcircuit -for relay |20.V 'I'he groundfcircuit for the Vcalledy subscribers lineY relay as hereinbefore' traced to the upperarmature and back contact of relay 124l is now transferred due to the release of relay through the right-hand winding of relay to ground. 'Ihis shunt circuit may be` traced from ground to the right-hand winding of relay |20, contacts of relays ||1 and to the brush and the corresponding Contact of bank 5 of connector C through the` lower winding of the called subscribers line relay to battery. This shunting, of course, prevents the rfull operation of the called subscribers line relay should a subscriber attempt to ring in before releasing the llnk'by the regular ring off. 'Ihe release of relay 606 will of course allow relay to release thereby completing a circuit for operating relays 108 and 1|| for'charging of battery 106. Relays in the trunk such as 109 and 1 |6 will release in the regular order and the operator should in the meantime withdraw the dial with its plug from jack 1|2 to completely'restore the control circuits to normal. Y

When relay ||2 operated to complete the connection between the calling subscribers line and the called subscribers line through the link the. switch |04 will be operated to select another idle link for subsequent calls; It will be noted that a circuitwill then be completed'for the stepping magnet 601 of the .switch |04 from battery `through its winding and self-interrupting contacts, left-hand armature and back contact of relay 606 which is now released, through the brush f,

and the vfirst terminal` of bank of switch |04 to ground at the second lower armature and frontl contact of relay ||2. The. magnet 601 will operate and advance the brushes of switch |04 to the l next link. If ground is encountered on this terfound, an idle link being identified by theabsence of ground on the corresponding terminal of bank Consequently the brushes of this switch will come to rest on terminals of the. first free link.

When the subscribers decide torelease the connectlon, either subscriber may operate her handset to send an alternating current impulse over back contact of relay |23 and its left-hand winds ing, upper inner armature and front contact of 75 relay I I2 back to the tip conductor. Relay |23 provides a looking circuit for itself from battery through its inner right-hand armature and front contact and right-hand winding to ground at the corresponding contact of bank 2 of connector C. The operation of relay |23 causes its weighted armature IZQ to vibrate and when it finally operates relay II2 will be shunted out by the ground applied by armature.k Il. Relay E23 together with relay I I2 complete a release circuit for the connector C. This circuit may be traced from battery through the winding of the stepping magnet I I6 of connector C, winding of relay II'I, vibrating contacts oi the stepping magnet I I6, the corresponding terminal of the called line in bank I and brush of this bank through the second upper armature and back contact of relay I I2, middle left-hand armature and front contact of relay |23 to ground at |329. Stepping magnet I I6 will step the connector forward until it reaches a normal position which is at terminal |25 of bank I. When the connector reaches this position the above-mentioned stepping circuit is opened and the holding circuit for relay |23 is opened at this position by the brush in bank 2 causing relay |23 to release which in turn, removes the ground from the. bank I and rel-eases relay III which, it will be noted, was operated when relay |23 was operated. The purpose of having relay III operated during the release of the connector switch was to shunt down the line relay of the called subscribers line and to clear the connector test wiper during release. This link is now available for other connections.

If the calling subscriber is on a party line and desires to call another subscriber on the same line two methods of establishing this so-called revertive call may be used. In one case the subscriber originates a call for another party on his own line by ringing the code of the other party. With this arrangement revertive calls cause no operation at office A.

If, however, a central cnice selective ring is available, the subscriber originates a revertive call in the same manner as a call to another line. The operator will answer the call and upon iinding that it is for another party on the same line can either ring the party for the calling subscriber, or he can wait on the connection until the subscriber has iinished ringing. As previously explained it would be necessary to operate the control key 'II3 if the operator wishes to speak to the calling subscriber. After either the operator or the subscriber has finished ringing the control key '|I3 should be restored and the connection can then be completely pulled down. At the end of the conversation the subscribers should hang up Without ringing off as a ring-oli signal would bring in a calling signal at the operators position.

A call will now be described from the coin box subscriber at |39 to another subscriber in the same exchange. In the present system the iirst, second and third lines may be arranged for pay station operation. The line to the subscriber at is shown as the iirst line. With this type of call the link and control circuits function as for a regular call until the wipers of the Iine-nders have come to rest on the called line. In this position and before the slow acting relay bill is operated a circuit is closed from battery through the stepping magnet III) and its interrupting contacts, the corresponding terminal and brush of bank 3 of switch Ill, the inner right-hand armature and front contact of relay S, outer right-hand armature and back contact of relay GII] brush and corresponding terminal of bank 2 oi switch IM, the brush and corresponding terminal of bank 2 of line-finder LF, upper inner armature and front contact of relay |05, middle righthand armature and back contact of relay 503, right-hand winding of relay 6I I to ground. Relay BII operates and closes a locking circuit for itself through its left-hand armature and front contact, outer right-hand armature and back contact of relay SIS, lower armature and back contact of relay '|35 to battery. The stepping magnet Ill) doesnct operate under these conditions. Relay BI I in operating opens the tip conductor of the trunk at its make-before-break contacts to again light the lamp TD4 which was extinguished when the operator'answered. The circuit over the tip conductor normally extends through the left-hand winding of relay 'II'I and as it isnow opened the differential relayoperates and the lamp 'ifi by the closure of a circuit for the lamp at its armature and front contact. When the vibrating armature 62| or of relay SII comes to rest, a circuit is closed for the opera,- tion of relay GIS over an obvious circuit. Ihis relay in turn closes a circuit for the operation of relay BIS over an obvious circuit. Relay SI3 in operating opens the locking circuit at its outer right-hand armature and back contact for relay BII causing this relay to release which in turn allows `relays 'II and ISIS to release. The release of relay 6| I closes the tip conductor thereby releasing relay lll to extinguish the lamp 104. The operator is thereby given a lamp signal after the plug has been inserted to indicate that a pay station is calling. The normal operating circuit for relay 6| I is opened as soon as relay SIU operates. This takes place soon after relay BII is operated as relay 6|!) is slow to operate. The

operations of selecting another subscriber from this point on are the same as in the call heretofore described. 'I'he operator will attend in the usual manner to the collection of coins.

In case a call is made from a subscriber in exchange A while the control trunk H32 is busy,

the operator will receive a flashing signal as soon as she starts to dial when the call is in progress, or if dialing is completed or in progress a flashing signal will be received as relay 6|| will, under these conditions, open and close the 4;

hand armature and front contact of relay IIlI-E which is operated at this time, to the normally open connection at the upper inner armature and front contact of relay IIll. If dialing has cornmenced on the previous call in progress or is completed, relay I I4 will be operated and the abovementioned circuit will therefore be completed at this time through the inner upper armature and front contact of relay IIfi through the inner right-hand armature and back contact of relay SIS, the left-hand winding of relay Sil, lower armature and back contact ci relay IE5 to battery. Relay BII will therefore operate and open the tip conductor of the trunk |32 and when the vibrating armature 62| cornes to rest a circuit will be closed for the operation of relay IE. This relay will in turn operate relay @I3 which releases relay SII and this relay releases in turn relays ISI@ and (M3. This cycle ci operation of relays SII, BIS and EIS will then be repeated to alternately open and close the tip conductor until the operator' operates her control key 1| 3 in the progress of completing the rst call. Therefore, the lamp 104 will be alternately lighted and extinguished due to the alternate operation and release of relay 1|1 to indicate to the operatorfthat a second calling subscriber is Waiting. When the operator disconnects on the first call lamp 104 will be lighted steadily as hereinbefore described as an indication to the operator to attend tc the waiting call.

n In case all of the links, as shown in Fig. 5, are busy When a call is originated, the calling subscriber receives the regular tone and the operator is signaled in the usual manner. When the operator answers the signal relay 1|6 will be operated and then relay 606, as hereinbefore described, to close a circuit for the operation of relay 6|0 from ground, winding of relay 6|0, inner righthand armature and front contact of relay 606, brush and the sixth contact 622, of bank 3 of switch |04 to battery.V It will be noted that in this case the switch |04 has been advanced to the sixth position as soon as the last, that is, the

fth link became busy in the same manner asthe switch is operated to engage a next idle link as hereinbefore described. Relay 6I0 now closes an obvious circuit for the operation of relay 603 and a circuit is therebyclosed for the operation of relay 'SI5 from battery, right-hand winding of relay 6|5, inner left-hand armatureand back contact of relay 6| 3, second left-hand armature and front contact of relay 603 through the sixth contact 023 and brush of bank I of switch |04, left-hand armature and front contact of relay 606, inner right-hand armature and front contact of relay 6|0 to ground at the outer left-hand armature and back contact of relayY 6I3. Relay 6|5 in operating closes a circuit for the operation of relay 50| as hereinbefore described and this causesa tone to be transmitted to the operator through condenser .6| 1 as hereinbefore described. Relay 6I6 is also operated over an obvious circuit by the operation of relay SI5. This relay in turn operates relay 6|3. Relay 6|3 now opens the circuit for relay SI5 and the relays 6|5, 0|6 and 5|3 are releasedin turn. Relay 6|5 is then reoperated and the cycle of operation and release of relays SI5, 6|6 and 6|3 are repeated. An intermittent tone is therefore sent to the operator to indicate that a call is waiting and that all links are busy. It should be understood that this interrupted tone is also transmitted to the calling subscriber under these conditions through the induction coil 600 and the line relay |06 when the operatoranswered the call to indicate to the calling subscriber that he will have to Wait kfor an Vinterval before he can receive attention.

Under these conditions the stepping magnet 601 of the switch |04 comes -directly under control of Vthe operator who may now test each link to ascertain whether it is actually busy. In order for the operator to test these links he will have to dial under these conditions, the switch |04 will thereby be operated to advance its brushes to the seventh position. The circuit forgthe stepping magnet 601 When relay 1I6 releases in response to this impulse may be traced from battery through the winding of this magnet, the sixth Yterminal 624 and brush of bank 4, middle righthand armature and front contact of relay 606, upper outer armature and back contact of relay 135, upper armature and back contact of relay 1I6 to ground at the upper outer armature and back contact of relay 122. The bank terminals 1 to on banks 5 and 6 of the switch |04 are Vto operate as usual.

multipled back to terminals Ito res'pec-` tively, thereby enabling the operator to monitor and ascertain if the first link is busy, that is, in this case the tip and ring conductors are extended through terminals of banks 5 and 6 to the first link. The operator then dials 1 again, for the next succeeding linkand to test this link, and will dial l for each succeeding link to test it.

When a call is originated by the operator at D, she inserts plug 1|4 into jack 1I5, causing the operation of relay 109 as usual. Relay 108 is thereby disconnected from the line and causes the release of relays 108 and 1| I. The release of relay 'III closes a circuit for the operation` of relay 10| from battery, winding of this relay, upper armature and front contact of relay '1|I, outer right-hand armature and back contact of relay 503. Relay 10| closes the tip and ring conductors throughr to relay 1|5, causing this relayV Relay 1|6 inv operating causes the operation of relay 606 and relay 606 closes a holding circuit for relay 10|. As a ground is supplied by all the line relays such as |06 through terminals of bank I in the line-finder LF, the stepping magnet ||0 for the line-finder will step the line-finder over the terminals of all the lines until the twenty-fifth position terminal is reached in lever I which terminal is allotted to mark the operators finding position. lIn this position there is no ground connection and relay 6|0 will operate as usual and open the stepping magnet circuit. Relay 603 is now operated over an obvious circuit. The finder having found this position and with relays operated as mentioned the operator may now proceed to dial the digit of the desired number in the exchange A. The link circuit functions in response to dial pulses as before in selecting any subscribers line. However, after conversation is completed and before removing a cord, the operator will dial a special digit. This allows relay 4 to release by being short-circuited and vthus closing a circuit for the operation of relay I I2 as relay |20 is operated as usual. The purpose of operating relay ||2 is so that the operator maythen operate her control key 1I0 and her ringing key 1I9 to send out a short pulse of ringing current. This ringing current will energize relay Y|23 as heretofore described, allowing the link circuit to restore as in a regular ring-ofi signal as previously described. The operator then restores the control key 1|0 and operates the release key 1I0 and then disconnects by removing her plug from the ack 'I I5 and the dial cord from jack 1|2 as usual. The operator may test succeeding links in this manner by dialing 1 as hereinbefore described. The dialing of 1 will step the switch |01 from one link to another as described. Under these circumstances if a link is kfound held busy and there is no conversation taking place Yover the link, the operator may release the link by sending a short ringing impulse over the trunk to operate relay |23 and release the'link as described.

In cases where the switch |04 has stepped to the sixth position, due to all links being busy, and no call originates, and then a link becomes idle, the switch |04 will step to the idle link. When one of the links becomes idle the brushes of the associated connector C, as hereinbefore described, will be restored to the twenty-fifth terminal |25. In this case, therefore, a. circuit will be closed for the stepping magnet 601 of the switch |04 as follows: From battery through the Windingof the stepping magnet 601, its pulsing contacts, left-hand armature and back contact of relay 606, the sixth terminal 623, and brush of bank I, terminal of the released connector bank I and brush thereof, upper middle armature and back contact of relay I I2, the associated back contact and armature of relay 6I0 to ground at 620. This circuit steps the switch |04 to the seventh position where the ground over the sixth contact 623' willl be replaced by a ground on the remaining terminals of bank I of switch |04 so that the switch will continue to step until an idle unguarded terminal is found corresponding to an idle link. That is, when switch |04 returns to a normal position, brush of bank I of switch |04 will rest on the terminal of the first link. If this link is busy there will be a ground on this terminal from the second lower armature and front contact of relay I|2 in that link and the switch will continue to operate until an idle link is found.

In case a toll call is incoming for a subscriber at the exchange A, the remote control operator at D inserts the plug 1|4 of her cord into the jack |32 of the talking or toll trunk |03 of Fig. 1. This toll trunk terminates at the oice A in exactly the same manner as an ordinary subscribers line, that is, it terminates with the tip and ring conductors the same as subscriber at |00 in line-finders and connectors and in a line relay such as |06 shown in Fig. 5 by box |34 and in the common control circuit shown in Fig. 6. The operator will then ring with her cord circuit ringing key in the usual manner and this brings in the calling signal 104 over the remote control trunk |02 in the same manner as if a call originated from a subscribers line in the exchange A. She answers this signal with a cord and challenges so as to make sure that the control trunk is actually connected to the toll trunk |03 as there is the possibility that a subscriber in exchange A might have originated a call at the same moment and obtain connection to the control trunk. Ii the toll trunk |03 has secured the connection over the control trunk |02", the operator will follow' the regular operating procedure for a call from one subscriber to another in the exchange A. When the called subscriber answers, the operator completes theconnection from the jack, such as |35, on. which the incoming toll call is waiting to the jack |312 of the tollv trunk |03 by means of an ordinary cord circuit I33, thereby completing` the toll connection to a subscriber in an exchange A. At the end of conversations. ring-off signal from either sub-- scriber will release. the link and will also indicate to the operator thatv the connection has been` taken down as is well known in the art.

' If a toll' call connection is desired by a subscriber in the exchange A, and such. toll callV is.

vlikely. to require some time to complete, the operator should request the calling subscriber to hangV up and await a call. The operator then obtains the connection to the distant subscriber over jack |35Y and completes the connection to the connection to the desired subscriber, as usual. The operation when the subscriber rings 0E is the same as on an incoming toll call.

If reference is now made to Figs. 6, 8 and 9 arranged in accordance with Fig. 3, descriptions will be made of calls between the step-by-step office F and exchange A. When the subscriber, for example at IOI, in the step-by-step oflice F desires a connection to a subscriber in exchange A, a connection is established in the usual manner from this subscriber through the usual switches such as a line-finder |06, a selector |01 and a connector |38 to a trunk line |09, leading through the manual oice B to the exchange A. As shown in Fig. 1, the trunk |99 also terminates in oice B in a multiple jack |36 at the control operators position at D. When the wipers. of connector |93 land on the terminals TR, EC and C of the trunk |99, as shown in Fig. 8, a circuit for lead C is completed to cause the operation of relay |31. 'Ihis relay disconnects relay |38 from the terminals of the right-hand windings of repeating coil |39, and closes a circuit for the lamp |40 in the manual oillcel Bl to light this lamp thereby busying the multiple jack 805 at the manual oiiice. As soon as ringing current is placed on the tip and ring conductors from the connector |08, a relay in the connector circuit, not shown, operates to complete a circuit for relay |42 from battery through the upper windu ing of this relay over terminal EC to the connector. Relay |42 operates and closes at its upper armatures and front contacts, direct connections through the left-hand and right-hand windings oi repeating coil |39 permitting ringing current to be transmitted through the coil over the trunk |09 to exchangeA. During the ringing period the line relay B06 is operated by the induced ringing current through the repeating coil |43, tip and ring conductors, the right-hand armatures and back contacts of relay 801, outer right-hand armature and back contact, and leithand winding of relay 806. Relay 806 closes a circuit for the operation of relay 60|, 602 and the relay 900 in a control trunk 902 modied to provide for alternating current dialing but otherwise similar to trunk |92. A tone is transmitted through the operation of relay 60| to the calling subscriber as induced through the lower winding of relay 806 over the tip and ring conductors over coils |43 and |39 in the same manner as hereirrb'efore described` in connection with calls from a local subscriber in connection with Figs. 5, 6 and '1. In general in the following circuit descriptions only such circuits that differ from the circuits described in connection with Figs. 5, 6` and 1 will be traced in detail. Relay 909 closes a circuit for' relay 90|, which opens the circuit for relays 9| and 903 to cut off the charging battery. Relay 908 in releasing closes a circuit for the line lamp 90'4 from battery' at dial jack 9|2, right-hand contacts' of relay 908, inner left-hand armature and back contact of relay 909, lamp 904, contacts of the control key 9|-3 to ground.

The operator in answering inserts plug 1-|4 into jack 9|f5 thereby causing the operation of relay 909 from battery' through the winding of' this` relay and contacts of jack 9|5. Relay 909- inV operating opens the. lamp circuit and closes a circuit forv relay 9|l6 which is responsive both to direct current and alternating current'. The circuity in this case. extends from battery at the' upper inner armature and back contact of` relay 9|f8, right-hand winding` of relay 9|1, contacts of relay 909, ring conductors of brush 902, contacts of relay 90|, lower right-hand winding of repeating coil 92|, contacts of relay 922, upper `winding of relay 9|6 to ground at contacts of relay 922. It also closes a circuit over the lefthand winding of relay 9|1, contacts of relay 909, contacts of the release key 9| 0, the tip conductor, contacts of relay 90|, upper right-han'd`winding of repeating coil 92|, make-before-break contacts of relay A6H, winding of relay 923 to ground. Relay 923 is marginal and does not operate in this circuit. Relay 9|6 in operating closes a circuit Vfor the operation of the relay 606`1'rom battery, winding of the stepping magnet 601 and its Vibrating contacts, winding of relay 606, armature and front contact of relay 9|6, lower outer armature and back contact of relay 922, to ground. Stepping magnet 601 does not operate in this circuit. Relay 606 in operating closes a circuit for the stepping magnet 8|0 of line-linder LF-B from battery through the winding of this magnet and interrupting contacts, first terminal and brush of bank 3 of switch |04, inner righthand armature and front contact of relay 606, outer right-hand armature and back contact of relay 6|0, brush and first contact of bank 2 of switch |04, brush and a terminal of bank of line-finder LF--B to ground at the corresponding line relay such as 806. As hereinbefore described, the stepping magnet 8|0 will now operate until the line-nder LF-8 nds the calling line terminals. When this takes place relay`6|0 operates over a circuit as hereinbefore described,

as the shunt circuit for relay 6|0 is removed by the operated condition of relay 806 of a calling line, ground having been removed from the sleeve terminal to the brush of bank of line-finder LIL-8. The operation of relay 6|0 closes a circuit for relay 603. As the holding circuit for relay 806 is now shunted as hereinbefore described this relay releases and removes tone from the calling subscribers line.

The operator now obtains the number of the desired subscriber and inserts plug 930 into jack 9|2 and operates the dial key 932. This changes the direct current connection through the pulsing contact of dial 13| to the alternating current source 933 to prepare the alternating current dialing circuits for the pulsing relay 9|6. When the operator dials the number of the desired subscriber the off-normal contacts of the dial close an obvious circuit for the operation of relay 9 |8 which closes the alternating current dialing circuit for relay 9|6. This circuit may .be traced from the alternating current source 933, operated left-hand contacts of dialing key 932,

` pulsing contacts of dial 13|, tip contacts ofplug 930 and jack 9|2, right-hand operated contacts of key 932, lower inner armature and front contact of relay 9I8, outer left-hand armature and front contact of relay 909, ring conductor of trunk |02, lower armature and front contact of relay 90|, lower right-hand winding of repeating coil 92|, contacts of relay 922, the condenser and lower winding of relay 9|6 to ground at contacts of relay 922. Relay 9|6 responds to alternating` current dial pulses over the trunk and the stepping circuit is completed on each release of relay 9|6 for the stepping magnet 8|6 as follows: from battery through the winding of this magnet 8|6, winding of relay 8|1, contacts of relay 8||, first terminal on brush of bank 4 of switch |04, middle right-hand armature and front contact of relay 606, contact of relay 935, armature and back contact of relay 9 I6, to ground 8|4 from battery, inner left-hand armature and,

front contact of relay 603, inner left-hand arma# ture and front Contact of relay 8|1, upper windt ing of relay v8|4 andY ground. Relay `8|4 locks through its upper winding from this battery at relay 603 through its upper middle armature and` front contact. The operation of relay 8|4 re-r moves the calling subscribers from the connection. On completing the dialing the wipers of the connection switch C-8 rest on the terminals of the called line. The pulsing relay 9|6 remains operated and the relay 8|1 is released.

vIf the called line is busy the circuits operate as hereinbefore described. If the called line is idle when relay 8|1 releases, relays 8|| and 820 operate as hereinbefore described and the operator is connected through trunk 902 to the called subscribers line. The operator will then ring the called subscriber by rst operating the control key 9|3. This will now operate relay 923 over a circuit from battery to the repeating coil 940, contacts of jack 9|5, contacts of control key 9|3, contacts of release key 9|0, tip conductor of trunk 902, upper armature and front contact o1' relay 90|, upper right-hand winding of repeating coil 92|, make-before-break contacts of relay 6| Winding of relay 923 to ground. Relay 923 in operating closes a circuit for the operation otre-- lay 922 and relay 9|6 releases. Relay 922 operates relay 935. The operator then actuates the ringing key 9|9 to cause the operation of the alternating current responsive relay 936 from the alternating current source, contacts of ringing key 9|9, the ring conductor, lower armature and front contact of relay 90|, lower right-hand winding of repeating coil 92|, contacts of relay 923, the condenser and the winding of the relay 936 to ground. Relay 936 closes an obvious circuit for the operation of relay 924, and places a holding ground on the locking circuit for relay 606 to maintain this relay operated and closes an obvious circuit for the operation of relay 935. The operation of relay 924 closes a circuit from the ring conductor of the trunk` 902 over the called subscribers loop to ground at the upper armature and front contact of relay 924, to the upper inner armature and front contact and the lower armature and front contact of this relay. Relay 924 in operating removes the shunt to ground across the operating winding of the called subscribers line relay allowing this line relayl toy trunk |09. Should the operator desire to remain on the connection for monitoring the operation of the circuits are as hereinbefore described. If the operator, however, pulls down the cord by removing plug 1|4 from jack 9| 5, the connection between the subscribers is established as before through the link and the control circuit is released. The ring-olf takes place as hereinbefore described in connection with calls between sub- Each time relay 924 releases the Scribers Y in exchange A by the operation of relay 823.

If the subscriber at in the exchange A,

desires to establish a connection with the subscriber at 101 in the step-.by-step cnice F, the following operations take place: The subscriber at |00 rings in the. usual manner and causes the lamp 904 to light before the operator at D as hereinbefore described. After the operator has inserted her lplug '114 into jack 915 to answer the call and receives the desired subscribers number from the calling subscriber, the operator will connect the dial 931 and 'operate the dial key 932 and thereby changing the circuit for alternating current control of the impulse responsive relay 916. The operator then vdials the rst digit of the desired number, which digit is the step-bystep office digit, causing relay 9-16 to respond in the usual manner and cause the connector C-8 to step to the terminals of the trunk 109, leading to the step-by-step voffice F. When this trunk has been found the relay 801 in the trunk circuit will operate Afrom battery through its upper winding, the corresponding 'contact and brush of bank 5 of the connector C-8 second lower armature and front Contact of relay 811, outer right-.hand armature and back contact of 'relay 811, lower inner armature and back contact of relay 924 to ground. The operation 'of relay 801 closes the trunk circuit from the connector C-8 to re.- peating coil 143, the operator then restores her dialing key 93| and operates 'the control key 9 I3. The operation vof this key causes as hereinbefore described the operation of relay 923 which in turn causes the operation of relays 922 and 935 and release relay 916, a path is thereby prepared for the ringing current responsive relay 936. The operator vnow operates her ringing key 91'9 and thereby causes alternating current ringing signals to be transmitted out over the trunk 109. The relay 936 operates as usual to cause the establishing of 'the connection by the operation of relay 924 for the ringing current over the trunk 109 through repeating coil 143. In response to this ringing current at the step-by-step ofce, the impulse relay 138 is operated over the lower winding of relay l138 and normal Acontacts of relay 131. The operation of relay 138 closes a circuit at its armature and front contact for the establishing of the usual line-lnder, such as 108, over conductors R-Z and T-2 to a first selector, such as 1-01, to prepare the circuit for dialing as is well known in the art. After the operator has received the usual dial tone she will proceed with the dialing of the remainder of the number of the desired subscribers line in the step-by-step exchange F. This is done in the usual manner by the operation of the dialing key 932 and the operation of the dial l931. The dial pulses extend in this instance over the ring conductor through the right-hand winding of repeating coil 143, back to ground over the tip conductor at the upper armature and front contact of relay 924. These pulses will be repeated through the repeating coil 143, trunk 109, through the lower winding Vof relay 138 which will respond accordingly. This relay in responding will set the proper switches at the step-by-step olce to the terminals of the called subscribers line over the line-finder 106, first selector 1'01 and connector such as 108. On completion of the dialing the switches at the step-by-step cnice will establish aground connection to the lead CT to cause the operation of relay 142 from battery through `the upper winding of this relay to ground over lead CT. Relay 142 in operating closes a holding circuit for impulsing relay 138 from battery, lower outer armature and back Contact of relay 131, lower inner armature and front contact of relay 142, lower inner armature and back contact yof relay 13'1, upper winding of relay 138, lower outer armature and front contact of relay 142, upper outer armature and back contact of relay 131 to ground. This is to maintain relay 138 operated after the operator has restored her dial key 932. After the dial key is restored relay 936 releases which in turn releases relay 924 and the operator can then ascertain the condition of the called subscribers line whether it is busy or idle. If the called line is busy the regular busy tone is received by the operator and on receipt of the busy tone the operator will operate key 145 to release relay 142 by a circuit through its lower winding. The windings of relay 142 are differential. holding rcircuit for relay 138 permitting the stepby-step office circuits to release. The operator will then establish a connection back to the call- Relay 142 `in releasing opens the ing subscriber in exchange A as hereinb'efore described and advise that the line is busy and take down the connection as usual. If the called line is idle the control operator will receive a ring back tone from the step-by-step ofce F. 'On receipt of 'this tone the control operator vwill disconnect from the trunk Aand pern mit the calling subscriber to be connected through the engaged link to the step-by-step oflice as usual. When the step-by-step oice subscriber answers conversation may be conducted. After conversation the step-by-step subscriber restores the receiver permitting the operation of relay 13'1 and causes the release of relay 138 and thereby releasing the circuit equipment at the step-by-step 'of'ce which in turn will release 'relay 142. The calling subscriber in office A will then release the circuit in her office by the usual ring-off signal.

If a toll connection is desired for va subscriber in exchange A a toll operator at the manual exchange B will insert her plug 114 into jack `136 which is multipled to her 'position 'from the trunk 109. This causes the operation of relay 131 over the sleeve connection through the jack 13S. Relay 142 also operates from battery, upper winding of relay 142, contacts closed by jack 136 to ground. The operator will then ring from her cord which causes the operation of the line relay 806 at the exchange A. Relay 142 closes connections across the lcondensers 146 and 14-'1 through repeating coil 139. The control operator at B will be called in the. usual manner, that is in the same manner as this operator was called when a subscriber at the step-by-step cnice was calling. The connection to a desired subscriber in exchange A is then. completed by the control operator in the usual manner and when the connection is completed between the subscriber in exchange A Vand the trunk 103 the operator will extend the toll connection vthrough jack 136.

With the Figs. 5, 6 and l0 arranged as shown in Fig. 4, descriptions will be made of the operations of these circuits when instead of the remote control trunk 102 a phantom circuit is used as a remote control trunk. Two ordinary telephone oircuits 1001] and 1801 may rextend from the exchange A to vthe manual exchange B and the phantom circuit derived from these two trol trunk, by tapping off at the mid-points of the repeating coils at each end as shown in Fig. 10. The circuits at both ends of the phantom trunk are but slightly different from the equipment at both ends of trunk |02 shown in Fig. '7. While the operations of the link shown in Fig. 5 and the control circuit of Fig. 6 are the same as when they are used with the remote control trunk |02, there are slight differences in the circuit arrangements for the phantom trunk. The following descriptions of calls using the phantom trunk will therefore omit in general, circuit details already described. In a call from a subscriber at |00 to another subscriber in the same exchange, the subscriber calls up as usual and causes the operation of relay |06. This causes the operation of relay 60| to send the tone to the calling subscriber, and the operation of relays 602 and |002. Relay |002 is operated over a circuit from battery through the upper winding of relay |002, contacts of relay 603 to the ground at relay |06. It should be noted that relay |002 is only momentarily operated as relay 602 operates at the same time and being slow in operating it closes a circuit through the lower winding of relay |002 from battery lower winding, right-hand armature and front contact of relay 602 to the ground at relay |06. 'I'he windings of relay |002 are differential. This relay will therefore release and be maintained in nonoperated condition. The momentary operation of the relay |002l opens the circuits for the normally operated relay |003 to cause this relay to release. The circuit for relay |003 may be traced from batteryat the terminals of jack |004, contacts of release key |005 and control key |006, contacts of relay |001, armature and front contact of relay.|003, winding of this relay, the left-hand windings of repeating coil |008, the tip and ring conductors, the left-hand windings of the repeating coil |009, tip and ring conductors of the telephone circuits |000 and |00|, right-hand windings of the repeating coil |0|0, the tip and ring conductors, right-hand windings of repeating coil |0||, armature and back contact of relay |002, make-before-break contact of relay |0|2 make-before-break contact of relay 6||, windings of relays |0|3 and |0|4 to ground. This circuit normally holds relay |003 operated but due to the resistance of the winding of this relay, relays |0|3 and |0|4 do not operate normally. The release of relay |0|4 closes a circuit for the lamp |0|5 from battery at the terminals of jack |004, contact of release kev |005 and control key |006, contacts of relay |001, amature and back contact of relay |003, lamp |0|5 to ground. The operator answers this call by inserting a plug into jack |0|6 and this operation closes an obvious circuit for relay |001 which opens the lamp circuit causing it to be extinguished. Relay |001 in operating also closes a circuit for relays |0|1 and |0|4. The circuit is the same for relay |0| 4 as previously traced to the repeating coil |008, then through the winding of relay |0|1, contacts of relay |0|8, contact of ringing key |0V|9, resistance |020, contacts of relay |001 to battery at the terminals of jack |004. Relay |0|3 does not operate in this circuit due to the resistance |020. Relay |0I4 in operating closes a circuit for the operation of relay 606, the circuit extending from battery through the stepping magnet 601 of switch |04 and its interrupting contacts, winding of relay 606, armature and front contact of relay |0|4, lower outer armature andback contact of relay |0|2 to ground. The operation of relay 606 causes as hereinbefore described the line-finder LF to iind the calling line and when the calling line has been found the tone is removed and the tip and ring conductors completed to the operator at the remote control ofce. The circuit extending through repeating coils |0||, |0|0 over trunks |000 and |00| serving as tip and ring conductors, respectively, repeating coils |009 and |008 to the operator over the jack |0|6.

The operator now obtains information as to the number of the desired subscribers line and the operator then connects her dial |022 to jack |004 and thus transfers the control of the relay |0|4 to the pulsing contacts of the dial. 'Ihen by operating the dial she will select the desired scribers line over the connector C in the usual manner, the pulsing relay |0|4 responding to the pulses and closing and opening the pulsing circuit that extends to the lower armature and back contact of relay |023, the armature and back Contact of the pulsing relay |0|4 and the lower outer armature and back contact of relay |0|2 to ground.

Should the called line be busy, the connector brush of bank 5 will encounter ground and relay |20 will not operate as usual under these circumstances. Therefore, when relay ||1 releases a circuitrwill be completed from ground corresponding terminal and brush of bank 2 of connector C to contacts of relays ||4, |20, ||1 and 6| 3, left-hand winding of relay 6|5, upper inner armature and back contact of relay |023 to battery. Relay 6|5 operates and this relay in conjunction with relays 6|6 and v6|3 causes a tone to be produced as hereinbefore described and conducted through condenser 6|1 through the upper outer armature and back contact of relay |023, upper winding of relay |025, upper lefthand winding of the repeating coil |0| I, contacts of relay 603, lower left-hand winding of repeating coil |0||, lower armature and back contact of relay |026 through the lower windings of the retardation coil |025 to ground. This tone is transformed through the right-hand windings of the repeating coils |0|| over the telephone circuits |000 and |00| to the operator. Under these conditions the operator will now determine whether the line is actually busy. The operation of the control key |006 closes a circuit from battery through winding of relay |028 to ground at contacts of relay |0|8. Relay |028 shunts out the resistance |020 from the trunk circuit by connecting battery from the control key |006 through the right-hand armatures and front contacts of relay |028 through contacts of the ringing key |0|9, contacts of relay |0|8, winding of relay |0|1 to the trunk.V This causes the operation ofrelay |0|3 in series with the pulsing relay |0|4. Relay |0|3 closes an obviouscircuit for vthe operation of relay |0|2. Relay |0|2 transfers the control circuit to relay |029 to cause it to operate. This circuit may be traced through the upper inner armature and front contact of relay |0|2, contacts of relay |026, upper -winding of relay |029 to ground. Relays |0|3 and |0|4 are released and relay |0|2 is held operated by relay |029 over an obvious circuit. The operation of relay |0|2 also places a holding ground for maintaining relay 606 operated in place of the ground supplied through the contacts of relays |0|4 and |0|2. Relay |0| 2 closes an obvious circult'for the operation of relay |023. This opens the cir- 'cil cuit for relay 6|3 and the busy tone is stopped. Relay is now operated by a circuit closed from battery, upper inner armature and :front contact'of relay |023, lower Winding of relayl to ground. This enables the operator to challenge on the called line by the closing of the tip and ring conductors through contacts of relay from the connector to the operator. The operator may now ascertain the condition of the line and if it is idle may ring down in the usualv manner by operating the relay |03| over a circuit from the alternating current source through the operated contacts of the ringing key |0|9, contacts of relay |0|8, contacts of the ringing key |0| 0 over the trunk circuit, lower right-hand armature of contacts of relay |002, upper inner armature and front contact of relay |0-|2, condenser |-032, alternating current responsive relay |03| to ground. This relay in operating closes a circuit for the operation of relay |026 which closes a connection from ground, upper outer armatureand front contact of relay |026 over the tip conductor tothe called subscriber, back over the ring conductor, the lower outer armature and front contact of relay |026, over the trunk circuit to the alternating current source at'the operators ringing key |0|0. Theroperator may then disconnect by removing the plug from jack |0|6 and permitting the connection between the calling subscriber and the called subscriber to be established as hereinbefore described. If the line is busy the operator will release the control key |006 and operate the release key |005. The operation of the release key momentarily opens the trunk circuit and releases rel-ay |029 which then releases relays |0|2 and |023. Relay |023 is slow in releasing so a momentary circuit is therefore closed for the release of relay ||4. The momentary circuit extends from battery, lower winding of relay ||4 and its lower inner armature and front contact, upper outer armature and back contact of relay |'0|2, lower inner armature andl front contact of relay |023, contacts of relaysll'l and |20,

lower inner armature and front contact of re-A lay ||l|A to ground at the corresponding terminals and brush of bank 2 of the connector C. The operator will thereby be able to talk to the calling subscriber over the calling loop and the normal contacts of relay ||4 as hereinbefore described.

On the other hand, if the called line is idle a circuit will be completed for relay |20 when relay Hl is released. This relay in turn closes a circuit for relay Relay in operating completes a locking circuit for relay |20. Relay also grounds the called line test terminal at the lower middle armature and front contact to prepare a circuit for relay H4- ifv the operator wishes to monitor on the completed connection. Relay connects the tip and ring of the called 'line to the trunk circuit.

The operator may now ring the called party but before the ringing key is operated, the operator must first operate the control key |006. The operation of this key causes the operation of relay |0|3 as hereinbefore described and this relay in turn operates relay |0| 2. Relay |0| 2 prepares a path for the ring relay |03| and opens the circuit for relays |0|4 and |0|3 which release and cause the operation of relay |023. The operator now operates the ringing key |0|9 to operate relay |03| and ring the called subscriber'as hereinbefore described byl first operating relay |026. v

If the operator wishes to monitor on the connection she will release the control key |006 and operate the release key |005. This releases relay |029 which in turn releases relays |0|2 and |0|3 allowingl relay |0|4 to operate. She will then dial the digit three, for example, and thus allow a ground impulse to momentarily shunt out relay ilflv and this relay in turn causes the operation of relay H2 which connects the calling subscribers line to the called subscribers line. The operator may release the trunk by withdrawing the cord as in ordinary connections. When thefoperator removes her cord from jack |016, relay i007' releases but as this relay is slow to release a circuit is completed for the reoperation of relay |003 from battery through the inner right-hand armature and front contact4 of relay |001, terminals of jack |001, winding of relay |003 over the trunk. This releases relay |0|1 while relay |003 remains operated from the battery and the dialing jack |004. Relay IOM' releases and opens the circuit for relay 606 and this relay in turn releases relays 6|0j and 603, which in turn release relay ll. the operation of relay ||,2 to connect the calling. and called lines together. When relay ||2 operates the switch |04 will select another idle. link.

On pay station calls the operations of the cir- This in turn causes cuits shown in Figs.v 5 and 6 are the same as hereinbeiore described and when relay 6| operates. and the operator is given special signal to indicate a pay station call after the plug is inserted I and the lamp |0|5 is extinguished when calling,4

line is found by line-iinder Fin a regular call.

On calls originated by the operator, the operator inserts her plug into jack` |0|6` and the circuits will function in the same manner as when the operator answers a local call, except thatl in this case provision is made whereby the twentyfth terminal in bank of line-finder F is allotted to mark the operators finding position. W'hen the finder finds this position the .operator may proceed to dial the wanted number. The link circuit functions as before after conversation is completed and beforeY removing her cord, the operator will dial a digit allowing the relay ||2 to operate. The operator will then actuate the control key |006 and send out a short impulse of ringing current which energizes relay |23 allowing the link circuit to restore as in a regular ringoff 'signall hereinbefore described. After sendingl out this short impulse of ringing current the operator restores the control key |006 and operates the release key |005 and then disconnects by removing her regular and dial cords.

What is claimed is:

1. In a "telephone system, subscribers lines, a. trunk, links for connecting a calling line with a called line, means for associating one end ofV said. trunk with an idle link, means for associating a calling line with said idle link, a signal at the other end of said trunk. and means operated in response to the seizure of a. calling subscribers line for operating said signal without associating the calling line with said idle link.

2. In a telephone system, subscribers lines, a trunk, links, means responsive to a subscriber initiating a call for signaling over the trunk, and means responsive to the answering of said signal by the seizure of the trunk for connecting the calling line to a link.

3. In a telephone system, subscribers lines, a

trunk, an operators position at one end of saidv trunk, links for connecting calling lines to called lines, means operative over a calling subscribers 

